Polarized relay



Jan. 5, 1943'. R. PEEK, JR 2,307,155

` POLARIZED RELAY O iginal Filed Nov. 16, 1958 4 Sheets-Sheet l /N VE /V TOR R. PgE/r, JR.

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Jan. 5, 1943. R. PEEK, JR

POLARIZED RELAY 4 sheets-smet 2 Original Filed Nov. 16, 1938 R I WP. WL R W f V, NNI. B

Jan. 5, 1943. R. 1 PEEK, JR

POLARIZED RELAY original Filed Nov. 16, 1938 4 Sheets-Sheet 5 /NVENTOR By A. PEE/r, JR.

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A TTORNEV Jan. 5, 1-943. R. L. PEEK, JR

POLARIZED RELAY Original Filed Nov. 16, 19258 4 Sheets-Sheet 4 /NVE N TOR A fe L. PEE/f, JR.

ATTORNEY Patented Jan. 5, 1943 POLARIZED RELAY Robert L. Peek, Jr., Townley, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Original application November 16, 1938, Serial N o. 240,687. Divided and this application February 27, 1941, Serial No. 380,764

2 Claims.

The invention is particularly suitable for use in a telephone pay station of the type illustrated in the O. F. Forsberg United States Patent 1,043,219, issued November 5, 1912, wherein a deposited coin is temporarily held upon a pivoted coin trap after the coin has actuated a coin trigger for causing the operation of a signal at the central ofiice to indicate that communication is desired and for establishing an energizing circuit for a polarized relay utilized subsequently in the disposition of the deposited coin. .At the termination of the conversation, battery potential at the central oliice may be applied to energize the coin relay whereby the actuation of its armature serves to collect the coin if the applied voltage is of one polarity and to refund the coin if the applied voltage is of the opposite polarity. The coin trap upon which the coin is temporarily held may be supported by a pivoted vane controlled by the relay to release the trap and direct the coin into the desiredY collect or refund channel. The operation of the relay also serves to restore the coin trigger to normal thereby reopening the electrical contacts controlled thereby.

An object of this invention is to simplify the construction and reduce the cost of manufacture of a coin relay While providing for eicient operation over a Wide range in energizing current and load.

A further object is to provide a polarized relay having a close margin between operate and nonoperate voltages.

In a preferred form of the invention the relay comprises magnetic material providing three vertical cores with a common base plate together with an armature pivoted on the center core and free to move so as to close the gap to either side core and open the gap to the other. The center core carries the main winding While two small auxiliary windings each in series with a varistor are placed on the side cores. When voltage is applied to the relay, current ilows through the main coil and one or the other of the side coils depending upon the polarity of the applied voltage. to the main coil except in the neutral position where it produces equal ux and pull at each gap. Whichever side coil is receiving current serves to unbalance the flux and thus produce a net pull in one direction. This small initial vpull The pull on the armature is primarily due r is opposed -by tensioning springs which hold the armature in the neutral position for voltages below that at which the operation is desired.

When such a relay is employed in a telephone coin collector it is preferable that the armature actuate the coin trap by means of a flexible arm of such stiffness that the armature can move through `approximately half its total travel before sulcient force is developed at the trap to overcome the maximum coin load. The load which such a flexible arm applies to the armature will vary linearly from zero at neutral position to a maximum at whatever point suicient force is developed to trip the coin trap. With such an arrangement the pull required to operate the relay and hence the operating current is independent of the coin load and is controlled solely by the tension of the springs which hold the armature in neutral position.

The form of the invention just described provides a polarized relay with a close margin between operate and non-operate voltages, not only because the operate voltage is independent of the coin load but also because the pull developed in the neutral position is proportional to the square of the current instead of being directly proportional to the current as in a relay employing a permanent magnet for polarization.

Referring to the drawings,

Fig. 1 is a View partly in section of the central portion of a telephone coin collector of the general type disclosed in the Forsberg patent;

Fig. 2 is a Wiring diagram of such a collector employing a polarized relay in accordance with this invention;

Fig. 3 is a side View of the polarized relay of this invention associated with the coin hopper;

Fig. 4 is a rear view of the polarized relay with the armature in neutral position;

Fig. 5 is similar to Fig. 4 except that the armature is in one of its operated positions;

Fig. 6 is a View partly in section of the upper portion of the relay taken `along the line 6-8 of Fig. 4;

Fig. 7 is a view of the upper portion of the relay with the associated coin trigger in coin operated position;

Fig. 8 is an enlarged rear view of the upper portion of the relay and spring contacts associated therewith where the yarmature is shown in an operated position;

Fig. 9 is a side view of the apparatus of Fig. 8;

Fig. 10 is a top View of the apparatus of Fig. 8; and

Fig. 11 is a side View partly in section of the tensioning arrangement for the relay armature.

Fig. l shows only a portion of a telephone coin collector of the type disclosed in the abovementioned Forsberg patent to which reference is made for further detaiis as to its general construction and methods of operation. A coin deposited by a subscriber after passing through a coin chute I5 in upper housing I6 drops into the coin hopper I1, actuates a coin trigger I8 and is temporarily retained upon a pivoted coin trap I3. The present invention is mainly concerned with the construction and operational features of the polarized relay the energizing circuit for which is prepared by the coin actuation of coin trigger I8, the relay in operating serving to restore coin trigger I8 to normal and release trap I9 to cause the deposited coin to be collected or refunded.

Referring more particularly to the relay as illustrated in Figs. 3, 4 and 5, brackets 2l, 22 suitably mounted in the lower housing 23 support the coin relay 23 which has an E-shaped core of magnetic material comprising a center limb 24` and two side limbs 25, 26. The main winding 21 for the relay surrounds the center leg while two small auxiliary windings 28, 29 surround the two side legs 25, 26. Mounted on the upper end of center leg 24 is a U-shaped pole-piece 30 (Fig. 6) between the upturned ends 33, 34 of which is pivoted the armature 35 by means of the pivoting screws 38, 39. The pole faces 36, 31 of the two side cores 25, 23 may be bent at an angle of about 6 degrees to the horizontal, so as to be parallel to the armature 35 in its operated position. Direct approach of armature to pole face is employed, and the pole face areas are made substantially larger than have heretofore been used in coin relays.

One or more varistors or asymmetrical conducting devices 43 which may be of the copper oxide type are mounted on corevarm 25 for connection in circuit with auxiliary winding 28 and similarly one or more varistors 4I are mounted onA core arm 26 for connection in circuit with auxiliary winding 29. Also mounted from the side cores 25, 26 is a bracket 44 having two spaced horizontal tabs 45, 46 for supporting the tensioning and restoringl springs for the armature. As shown more clearly in Figs. 10 and 11, one tensioning spring 41 has one end fastened to tab 45 while.its free end 48 is biased to rest on the other tab 45. Spring 41 near its free end has a stud 49 which rests upon the armature when the armature and spring 41 are in normal positions. For tensioning armature 35 against movement in the opposite direction a tensioning spring 58 is provided, one end of which is fastened to tab 45 with its free end 5I resting on tab 46. Spring 58 also has near its free end a stud 52v which bears against the armature 35 when the armature and the spring are in their normal positions. Members 41r and 58 are lightly tensioned springs employed 4for the purpose of centering the armature in Yits neutral position while two additional springs 53, 54 are employed for restoring the armature from one of` its operated positions to neutral position. Spring 53 is spaced above spring 41 with one end fastened to tab 46 and with its free end normally resting on stop 45 while spring 54 is spaced above spring ll'with one end fastened to tab 45 and its free end normallyj resting on stop 48. It will be apparent from Fig- 11 thaty when the armature isy moved to the operated position shown in that iigure, the armature will first lift tensioning spring 41 and with further armature movement the head of stud 48 will contact with the lower surface of the free end of spring 53 whereby both springs 41,

'53 are moved from their normal positions so that when the operating current is removed spring 53 will supply the main armature restoring force until stud 49 is free of spring 53 whereupon springs 41 and 58 serve to center the armaturein its neutral position. Similarly, if the armature 35 is moved to its other operated position from that shown in Fig. 11 such armature movement by means of stud 52 first deflects tensioning spring 58 and then deects restoring spring 54. Preferably, in each case the restoring spring 53 or 54 is not picked up until after the armature has completed about one-half of its travel from neutral to its fully operated position.

Armature 35 carries an arm 52 for actuating the coin vane 58 to release theV pivoted `coin trap I8. This operating arm comprisesfa` flat plate 53 fastened on top of armature 35 by screws 68, 8I and from this lat strip the arm extends outwardly beyond pole-piece arm 33 and then downwardly to a point adjacent coin vane 5B where arm 62 terminates in a horizontal piece 63 containing an elongated slot 34 for receiving a pin G5 carried by a short arm 66 pivoted at the point 61. It should be noted that the main portion of arm 62 between armature 35 and pin 65 comprises a flat strip of vmetal lying in a plane at right angles to the direction of its motion so as to provide a flexible connection between armature 35 and pin 65 for a purpose t0 be described later. Small arm 68 at its upper end has an elongated slot E58 for receiving a pin 69 attached to' coin vane 58 at a point substantially above the pivoting axis forthecoin vane. Asrshown particularly in Fig. 5 pin 69 projects through an arcuate slot 1I in side wall 18 of the coin hopper I1. It will be obvious from the above description that armature 35 will actuate coin vane 58 to release the trap I9 and discharge any coins thereon either into collect chute 12 or refund chute 13-in the same manner as described in the above-mentioned Forsberg` patent.

In order to provide a pivoting support for coin trigger I8, bracket 44 has an extension 14 terminating in two spaced lugs 15, 13 ap'ertured to support the pivoting pin 11 for the coin trigger. The counterweight 18 for the coin trigger normally rests on the upper portion of a stop 19 supported by the armature pivoting screw 38.

Bracket 44 by means of an upwardly extending portion also supports a Vhorizontally arranged electrical spring contact pile-up jointly controlled by coin trigger I8 and armature 35. 'AI'hispile-up comprises two electrical spring c ontacts`82, -83 normally biased to open condition, and a biasing spring 84 which is biased towards spring contacts 82 and 83 but normally restrained from closing these contacts by reason of the fact that coin trigger I8 in its normal position has a shoulder v'83 interposed in the path of the tip portion 81 of the biasing spring as shown in-Figf 3. However, as soon as coin trigger I8 is hit by a deposited coin the trigger in assuming its actuated position of Fig. 7 frees the biasing vspring 84 from shoulder 86 and allows the biasing spring t o move to the right as shown in Fig'mto close contacts 82, 83. Counterweight 18`- is prevented at this time from restoring the coin triggerto normal since tip 81 of the biasing-spring 84 now lies in the return path for shoulder 86 as shown in Fig. '1.

It will be obvious from Fig. 2 that the closure of contacts 82, 83 prepares an energizing circuit for the coin relay to enable the deposited coin or coins to be collected or refunded.

In order that the closed contact springs 82, 83 may be reopened and the coin trigger I8 restored to normal, there is pivoted about the pin 11 an angular member 88 having two spaced hori zontally extending legs 89, 98 resting on the top of armature 35 on opposite sides of the armature pivoting axis, and a vertical arm 9| which acts as astop against which the springs 82, 83 are forced by the actuation of biasing spring 84 when released by coin trigger I8. However, as soon as armature 35 has been deflected in either direction by the application of energizing current to the relay windings, member 88 will be moved counter-clockwise from its position shown in Fig. 6 or 7 to the position o-f Fig. 9 whereby the upper arm 9| forces the spring pile-up to the left far enough to free trigger shoulder 86 from the restraining iniiuence of the tip 81 of biasing spring 84, allowing coin trigger I8 to restore to normal while still maintaining contacts 82, 83 closed as long as the armature 35 remains in its operated position. When the energizing current for the relay windings is removed, armature 35 is restored to normal and arm 9| will likewise be moved clockwise to its normal position. Biasing spring 84 will follow this movement of arm 9| until tip 81 hits shoulder 86 as shown in Fig. 3 whereupon with the completion of the movement of arm 9I contact springs 82, 83 will be permitted to separate under their own tension.

Referring now to the wiring diagram of Fig. 2 for a telephone substation employing a coin collector of the type just described it will be apparent that when contacts 82, 83 are closed by the coin actuation of trigger I8, conductor 93 of the telephone line is connected to ground through the windings of the polarized relay. If the operating voltage for the relay applied at the central oice over conductor 93 is of such a polarity that current passes freely through varistor 40 but not through varistor 4I, then the current will now in series through auxiliary winding 28 and main winding 21 to ground and the armature 35 will be operated counter-clockwise to perform the functions previously described. On the other hand, if the applied voltage is of the opposite polarity the current will pass freely through varistor 4l but not varistor 40 and the current will flow in series through an auxiliary winding i 29 and main winding 21 to ground to cause the operation of the armature in a clockwise direction. It will, therefore, be seen that the relay is polarized by means of the oppositely poled varistors 48, 4I in circuit with the auxiliary windings 28, 29 whereby when the applied voltage is of one polarity current is permitted to flow through winding 28 but not winding 29 while when the voltage is of the opposite polarity current is permitted to now through winding 29 and not Winding 28.

As previously stated, the pull on armature 35 is primarily due to main coil 21 except at the neutral position where it produces equal flux and pull at the two gaps between the armature and the pole faces 38, 31. Whichever side coil 28 or 29 is receiving current then serves to unbalance the flux and produce a net pull in one direction, after which the deiiection of the armature to its fully operated position is due mainly to main winding 21. The small initial pull on the armature due to current in either winding 28 or winding 29 is opposed by one of the tensioning springs 41 or 50 and these two springs serve to hold the armature in its neutral position for applied voltages below that at which operation is desired.

`vThe arm 82 through which the armature 35 acts on the coin vane 58 is flexible and preferably of such stiffness that armature 35 can move through about one-half of its total travel before sufficient force is developed at the coin vane to overcome the maximum coin load. Hence, the load which arm 62 applies to armature 35 varies linearly from zero at neutral position to a maximum at whatever point sunicient force is developed at the lower end of arm 62 to trip coin trap I9. With such an arrangement the pull required to operate the coin trap and hence the operating current is independent of the coin load and is controlled only by the tension in springs 41, 50 which hold the armature in neutral position. At the half-way point in the armature travel one of the the heavy return springs 53 or 54 is picked up which balances the pull for the remaining half of armature travel so that when the applied current is removed the armature returns to the half-way point under the action of the deflected spring 53 or 54. At this point the spring contacts 82,83 open as previously described and the deiiected tensioning spring 41 or 58 restores the armature to neutral position.

Such an arrangement provides a polarized relay with a close margin between operative and non-operative voltage. This close margin can be realized because the initial operation of the armature is independent of the coin load and because the pull developed in the neutral position is proportional to the square of the current, and hence the operate and non-operate margin can be controlled substantially as closely as can be done for a simple unpolarized relay.

In order to have the desired pull characteristic in the above-described relay it was found desirable to employ a direct approach of armature to the pole faces, to make the pole face areas 38, 3'.' as large as possible, and to reduce the armature travel by the above-described coupling between coin vane 58 and the armature as compared with the amount of armature travel required if arm 62 were directly linked to coin vane pin 69. It has also been found desirable to make the center gap between the armature and the core portion 24 as small as possible and in the embodi ment shown this is accomplished by employing a U-shaped pole-piece 38 mounted cn top of center core 24 with a minimum air-gap between arms 33, 34 and the adjacent edges of the armature. In order to get armature 35 accurately centered in its neutral position, the relay construction is preferably such as to minimize any motion of the tensioning springs 41, 58 before they are lifted on their stops against which they are tensioned. In one particular embodiment of the invention it was found desirable to employ about 1000 turns for each of the windings 28 and 29 and about 14,000 turns for the main winding be accurately aligned to determine the armaturev posi-tion at which: it is tensionedv to meet operative and non-operative requirements.

What is claimed is:

l. A polarized electromagnet having a close margin between its minimum operate voltage and its maximum non-operate voltage comprising a pivoted armature mounted for limited rotative movement about its axis, electromagnetic means for deflecting said armature in a direction dependent upon the polarity o fvtheapplied voltage, lightly tensioned spring means biased to hold said armature in a neutral position for an applied voltage below that at which operation is desired, additional tensioned spring means effective on said armature only after said armature has been moved a substantial distance from its neutral position for applying a restoring force to move said armature back towards its neutral position' after the removal of an applied operating voltage, and means for coupling said armature to the useful load to be actuated thereby, said coupling means comprising an elongated arm extending in a substantially radial direction from the axis of said armature, said arm ,at its end remotefrom said armature vengaging said load, said 'arm having such nexibility in the direction of its rotative movement that said armature is compelled to move through approximately one-half its total travel before suiicient force'is developed at thc far end of said arm to actuate saidloa'd.

2. A polarized electromagnet having a close margin between its minimum operate voltage and its maximum non-operate voltage comprising a pivoted armature mounted for limited rotativel movement about its axis, electromagnetic means for deiecting said armature in a direction dependent upon the polarity of the applied voltage, lightly tensioned spring means biased to hold said armature in a neutral position for an applied voltage below that at which operation is desired, additional tensioned spring means eiective on said armature only after said armature has moved through approximately one-half its total travel from its neutral position for applying a restoring force to move said armature back towards its neutral position after the removal of an applied operating voltage and means for coupling said armature to the useful load to be actuated by said armature, whereby the load which said coupling 'means applies to said armature varies substantially linearly from zero at said neutral' position to a maximum at that Iadvanced armature position at which suicient force is developed'to overcome the inertia of said useful load, said coupling means comprising an elongated armhaving one end secured to ,said armature, said arm extending in a substantially radial direction from the axis of said armature, said arm at its end remote from said armature engaging said useful load, saidlarm for the major portion of its length being composed of a thin `flexible metal strip having its main surfaces lying in planes substantially parallel to a plane passing through the axis of said armature, whereby said arm is bent substantially under the force appliedv thereto by said armature.

ROBERT L. PEEK, JR, 

